As the death toll from the worst floods in a century climbed relentlessly in India’s southern Kerala state, Prime Minister Narendra Modi took an aerial tour, inspecting the massive damage that engulfed villages and cities, and announced emergency aid of over $70 million.

The situation is grim in the picturesque, coastal state famed as a tourist destination -- rivers, dams and reservoirs have overflowed following record monsoon rains that swept away roads and homes and forced more than 220,000 people to seek shelter in relief camps.

A massive rescue and relief effort has been stepped up as the scale of the disaster widens and distress messages continue to pour in from people stranded on rooftops and in remote villages.

Officials said the torrential rains in the last ten days have claimed 165 lives, but the toll since the monsoon arrived three months ago is 324.

Boats are reaching those marooned by the swirling waters, while about 30 military helicopters are pressing into areas inaccessible by boat.

“They are flying from first light to last light,” said navy spokesman, D.K. Sharma, as helicopters flew hundreds of sorties, distributing food and water and plucking survivors off rooftops. It is a challenging task because with much of the state swamped by floodwaters, there is no place for helicopters to land.

“It is unknown terrain, there are high-tension wires, there are trees, there are population, there are obstruction, all these make the situation very difficult,” Sharma said.

Describing the challenge for pilots, he said “the helicopter has to be hovered in a very, very steady position. Then you pick up the survivor and then move to the next one, and the next one. Yesterday one helicopter brought in 26 survivors.”

Local fishermen have also pitched in, plying their boats to rescue people.

Many victims were crushed under landslides triggered by the torrential rains – the state has received 37 percent more rain than usual due to low pressure over the region.

However, environmentalists also blamed the severe flooding on unplanned development and deforestation on mountain ranges in the north.

The northern and central parts of the state - which is home to 33 million people - have been hit the worst. Power, transport and other infrastructure has taken a huge hit and the international airport in the main city, Kochi, has been shut.

Kerala's chief minister, Pinarayi Vijayan, said the state faces an extremely grave crisis and the economic damage is likely to run into billions of dollars

“The nation stands firmly with Kerala in this hour," Prime Minister Modi tweeted after conducting an aerial survey on Saturday. He promised more assistance to the rescue and relief effort.

It could take months for a state with a tourist-dependent economy to recover.

The manager of a four-star hotel in Kochi, who did not want to be named, said business has been battered.

“There are no flights here," she said. "It's affected our hotel badly. I don’t think we will get customers in the near future.” With many water treatment plants damaged, she expressed fears that “we will run short of water also.”

The worst may not be over for the anytime soon – meteorologists are forecasting more rain for the state.